Answer: High-grade angiosarcoma

Histology: This is an unusual case. Superficially, the tumor has several of the features of pyogenic granuloma, in that it has an epithelial “collarette” around it, has a lobular architecture, and has more differentiated, bland blood vessels. However, deep within the lesion is an overgrowth of solid, cytologically malignant spindle cells, which at their periphery dissect collagen to form vascular spaces. These are the classic features of angiosarcoma. The more differentiated component of the tumor extended to the peripheral margins of the specimen. Because the superficial component is so differentiated, it is impossible to distinguish from a pyogenic granuloma in a superficial biopsy.

Discussion: Pyogenic granuloma would lack the cytologically malignant deep spindled component to the tumor, as well as the dissecting vascular pattern deep within the tumor. Spindle cell hemangioendothelioma is a benign process that is typically engrafted upon a pre-existing vascular lesion. Hence, it is tempting to put this case together as a pyogenic granuloma with associated spindle cell hemangioendothelioma. However, spindle cell hemangioendothelioma never grows in a sheet-like pattern and dissects collagen as the current case does. Spindle cell hemangioendothelioma would also not be associated with the cytologic atypia of the current case. Bacillary angiomatosis may have the appearance of pyogenic granuloma in areas, however, bacillary angiomatosis is typically associated with neutrophilic microabscesses with blue bacterial colonies.

Angiosarcoma classically arises in five clinical settings. The first is cutaneous angiosarcoma without lymphedema, which is typically seen in an older patient, located on the face and multifocal. The current case is best categorized as an example of this presentation. Angiosarcomas can also arise in patients with chronic lymphedema (Stewart-Treves syndrome), in the parenchyma in the breast of young women, in the deep soft tissue (where they appear epithelioid), and after radiation therapy. Radiation-associated angiosarcomas usually occur after a latency interval of seven years. The exception is post-radiation angiosarcoma of the skin of the breast, which can occur within three years of radiation therapy.